Causes of gigantism

From the time someone is born, the way their body grows is controlled by hormones produced by the pituitary gland in the brain. The most important hormone for growth is called growth hormone, also known as human growth hormone, HGH or GH.

Most children with gigantism have too much growth hormone, which makes them grow too much, too fast.

Gigantism is almost always caused by a benign tumour, also known as an adenoma, growing in the pituitary gland. Usually, there is no obvious reason for this, although it may be due to rare genetic conditions.

There are also rare genetic conditions that can cause gigantism without the child having an adenoma. Examples include Sotos syndrome, Beckwith-Wiedemann syndrome, and Weaver syndrome. You can learn more about rare genetic conditions here.

A similar condition to gigantism, known as acromegaly, can affect adults. Like gigantism, acromegaly causes abnormal growth, but instead of making the person grow tall, it causes other symptoms.

Symptoms of gigantism

Gigantism can appear in a child of any age, from baby to teenager.

The main symptom is accelerated growth, which means the child will be unusually tall for their age. Other features include:

• large head
• prominent forehead
• protruding jaw
• coarse-looking facial features, such as a broad nose
• very large hands and feet, with thick fingers and toes
• excessive sweating
• a very large appetite
• general weakness

Some people also get headaches, nausea, problems with vision and delayed puberty.

Diagnosis of gigantism

A doctor who sees a child who is growing unusually fast will need to ask some questions and do a physical examination, which might include checking height, weight, body proportions, senses, and stage of puberty.

Tests to diagnose gigantism include:

• blood tests – to measure the level of hormones, and sometimes other substances
• oral glucose tolerance test – to see how growth hormone levels change when blood sugar level is increased
• an MRI or CT scan – to look at the pituitary gland
• x-rays of the skull and jaw – to check bone thickness

It’s important to diagnose and treat gigantism as early as possible. If untreated, it can lead to problems such as diabetes, high blood pressure and arthritis.

Treatment of gigantism

Treatments for gigantism include:

• surgery – to remove or reduce the pituitary tumour
• radiotherapy – to reduce tumour growth and growth hormone levels
• drug therapy – to control growth hormones levels and symptoms, and shrink the tumour

Living with gigantism

When the condition is successfully treated, children with gigantism can have a normal life expectancy and avoid most of the complications caused by it. However, they may still have symptoms such as muscle weakness and restricted movement, and some may also have psychological problems. Because of their size, it may also be hard to buy them items such as clothes and shoes. Regular medical follow-up is needed to monitor the condition over time.

More information

• Use healthdirect's online Symptom Checker to check any symptoms and to find out what your next step should be.
• Try the healthdirect Question builder to help you prepare a list of questions for when you visit your doctor.
• Contact the Australian Pituitary Foundation.